Coating compositions are typically applied to sports equipment to protect the actual equipment, as well as any identifying indicia and any paint layers. For example, because conventional golf ball cover materials, i.e., balata, ionomer resins, and urethanes, suffer from abrasion and shear from repeated contact with golf clubs, golf ball manufacturers traditionally apply a coating to increase the abrasion resistance of the balls. In addition, coatings are used to improve the aesthetic quality of the equipment because of the high gloss. Traditional coatings, however, have not been entirely satisfactory to golf ball manufacturers or the golfing public.
Golf equipment manufacturers have been experimenting with various materials and manufacturing methods for coating golf equipment over the years in an attempt to further refine the manufacturing process. Conventional coatings generally include a clear primer coat and a clear top coat, although for certain applications a single clear coat may suffice. The primer layer is typically applied to promote adhesion or to smooth the surface roughness before the top coat(s) are added to the golf equipment. And, while coating compositions are generally free of pigmentation, they may contain small amounts of dye, pigment, and optical brighteners so long as they still allow for a bright ball cover. In addition, as briefly mentioned above, various identifying indicia may be applied either directly upon or alternatively upon the cover, the primer coat or the top coat.
Urethanes, urethane hybrids, polyesters and acrylics are conventional coating materials. In particular, a cured polyurethane top coat is most widely used as a protective coating composition material, which are typically either “one component” or “two component” systems. Such coatings may be classified as either water-based or nonaqueous solvent-based systems. One component systems are generally made up of minute polymeric particles (reacted or partially reacted) which are suspended or dispersed in one or more solvents. In contrast, the primary reactants in two component systems must be kept separate from one another until the actual coating need be applied to the golf equipment. Once the reactants are allowed to interact, however, polymerization occurs, which may be accompanied by or followed by evaporation of the solvent.
For example, a two component polyurethane system may include separate packages of polyol and diisocyanate, which are mixed together to yield a thermoset coating composition. In some cases, more than one curing mechanism may be used to cure the coating system, e.g., evaporation of solvent via ambient air in addition to the subjecting the coating to ultraviolet light. Examples of conventional polyurethane coating compositions are disclosed in International Publication No. WO 92/19656 and U.S. Pat. Nos. 5,459,220, 5,461,109, and 5,124,385.
While some conventional coating systems, including a few of those described above, do impart a measure of abrasion and impact resistance, a continuing need exists for improved coatings capable of providing enhanced abrasion resistance and adherence to balls without negatively affecting the performance of the coated object. In addition, there is a need in the art for coating compositions that have improved processing in non-optimal conditions, e.g., humid conditions. Moreover, a quick-cure coating composition that fully cures in all conditions is advantageous to reduce or eliminate any defects from wet transfer.